Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, PR China.
Int J Syst Evol Microbiol. 2024 Nov;74(11). doi: 10.1099/ijsem.0.006550.
Two Gram-stain-negative, aerobic, rod-shaped, non-endospore-forming bacteria, designated as strain MH1 and MH2, were isolated from branches of wilted pepper plants () collected from a farmland in Machong town, Guangdong, China, and investigated using a polyphasic approach. MH1 grew at temperatures of 4-42 °C (optimum 28 °C), with 0-6.0 % (w/v) NaCl and at pH 4.0-10.0 (optimum pH 4.0). MH2 grew at temperatures of 4-42 °C (optimum 28 °C), with 0-6.0% (w/v) NaCl and at pH 4.0-10.0 (optimum pH 5.0). Analysis of the 16S rRNA gene sequence indicated that MH1 belongs to and MH2 belongs to . Genome-based phylogenetic analysis further established that MH1 shares the closest evolutionary relationships with DSM 18929 and DSM 18941, and MH2 is sister to RW3S1. Whole-genome comparisons between MH1 and known species revealed average nucleotide identity (ANI) values up to 84.5%, as well as digital DNA-DNA hybridization (dDDH) values up to 28.3%, both substantially lower than the accepted thresholds for species delineation (ANI: 95%; dDDH: 70%). The ANI and dDDH values between MH2 and known species were at most 94.6 and 59.2 %, respectively. Additional biochemical and physiological analyses further support that MH1 and MH2 represent a novel species in and , respectively. Notably, the differences in carbon source utilization could differentiate MH1 and its close relatives in . The major fatty acids were iso-C, iso-C and iso-C for MH1 and were C, C ω7c/C ω6c (summed feature 8), C ω7c/C ω6c (summed feature 3) and C cyclo for MH2. Therefore, we propose a new species sp. nov., with MH1 (=GDMCC 1.3749=JCM 36317) as the type strain, and a new species sp. nov., with MH2 (=GDMCC 1.3750=JCM 36318) as the type strain. The MH1 genome has a size of 4.18 Mb and a GC-content of 67.19 mol%, while the MH2 genome has a size of 5.71 Mb and a GC-content of 63.12 mol%.
两株革兰氏阴性、需氧、杆状、非芽孢形成细菌，分别命名为 MH1 和 MH2 株，从中国广东省马冲镇农田枯萎辣椒植株的分枝中分离得到，并采用多相研究方法进行了研究。MH1 在 4-42°C（最佳 28°C）、0-6.0%（w/v）NaCl 和 pH 4.0-10.0（最佳 pH 4.0）的条件下生长。MH2 在 4-42°C（最佳 28°C）、0-6.0%（w/v）NaCl 和 pH 4.0-10.0（最佳 pH 5.0）的条件下生长。16S rRNA 基因序列分析表明，MH1 属于 ，MH2 属于 。基于基因组的系统发育分析进一步表明，MH1 与 DSM 18929 和 DSM 18941 最接近，而 MH2 与 RW3S1 姐妹关系最近。MH1 与已知 种之间的全基因组比较显示平均核苷酸同一性（ANI）值高达 84.5%，数字 DNA-DNA 杂交（dDDH）值高达 28.3%，均远低于种界定的可接受阈值（ANI：95%；dDDH：70%）。MH2 与已知 种之间的 ANI 和 dDDH 值最高分别为 94.6%和 59.2%。额外的生化和生理分析进一步支持 MH1 和 MH2 分别代表 中的一个新种和 中的一个新种。值得注意的是，碳源利用的差异可以区分 MH1 及其近亲在 中的关系。主要脂肪酸为 MH1 的 iso-C、iso-C 和 iso-C，而 MH2 的则为 C、C ω7c/C ω6c（特征 8 总和）、C ω7c/C ω6c（特征 3）和 C 环。因此，我们提出了一个新的物种 sp. nov.，以 MH1（=GDMCC 1.3749=JCM 36317）作为模式株，和一个新的物种 sp. nov.，以 MH2（=GDMCC 1.3750=JCM 36318）作为模式株。MH1 基因组大小为 4.18 Mb，GC 含量为 67.19 mol%，而 MH2 基因组大小为 5.71 Mb，GC 含量为 63.12 mol%。
